I e-mailed autocostruire via the website link and got a very quick reply. English is fair!
Just another thought, one could always try experimenting with a mu-metal screen between the inductors and the rest of the circuit. I guess one of the mechanisms for the EMI to be picked up are the component leads acting as aerials, so in this respect SM components have an advantage despite being a pig to solder.
Just another thought, one could always try experimenting with a mu-metal screen between the inductors and the rest of the circuit. I guess one of the mechanisms for the EMI to be picked up are the component leads acting as aerials, so in this respect SM components have an advantage despite being a pig to solder.
yes, a mu-metal screen (better if grounded) would suppress EMI, but would act again as a core material causing hysteresis and large eddy currents (a screen is a conductive solid piece); thus spoiling up the effort for air cored chokes.
Tripath on their evaluation boards provides grounded connection for a screen, but that case is simpler because inductors are cored, so concentrate most of the magnetic field inside the core.
But, since starn02 proved that there isn't much nasty EMI, i think it is better to try and add a screen or change for other chokes solutions only if someone finds interference.
Kanaddict, I don't think that the small angles between inductors is there to diminish mutual inductance: the chokes are too close and most of all they should be perpendicular to each other for this purpose. To me is only a problem of spacing.
Bye bye
Tripath on their evaluation boards provides grounded connection for a screen, but that case is simpler because inductors are cored, so concentrate most of the magnetic field inside the core.
But, since starn02 proved that there isn't much nasty EMI, i think it is better to try and add a screen or change for other chokes solutions only if someone finds interference.
Kanaddict, I don't think that the small angles between inductors is there to diminish mutual inductance: the chokes are too close and most of all they should be perpendicular to each other for this purpose. To me is only a problem of spacing.
Bye bye
dillo said:But, since starn02 proved that there isn't much nasty EMI, i think it is better to try and add a screen or change for other chokes solutions only if someone finds interference.
Kanaddict, I don't think that the small angles between inductors is there to diminish mutual inductance: the chokes are too close and most of all they should be perpendicular to each other for this purpose. To me is only a problem of spacing.
Bye bye
Thanks Angelo !
When I'll get my kit (probably september), I'll build it as indicated & see if there is any problem. Be sure that I'll post a little review.
Best regards,
dillo said:yes, a mu-metal screen (better if grounded) would suppress EMI, but would act again as a core material causing hysteresis and large eddy currents (a screen is a conductive solid piece); thus spoiling up the effort for air cored chokes.
Tripath on their evaluation boards provides grounded connection for a screen, but that case is simpler because inductors are cored, so concentrate most of the magnetic field inside the core.
But, since starn02 proved that there isn't much nasty EMI, i think it is better to try and add a screen or change for other chokes solutions only if someone finds interference.
Kanaddict, I don't think that the small angles between inductors is there to diminish mutual inductance: the chokes are too close and most of all they should be perpendicular to each other for this purpose. To me is only a problem of spacing.
Bye bye
A Faraday Cage maybe?
http://en.wikipedia.org/wiki/Faraday_cage
Hallo T-Amp Tweakers,
today i found good Information about Air Cokes on
www.colmar.com/Shavano/inductor-info.html
Greetings from Germany
Jürgen
today i found good Information about Air Cokes on
www.colmar.com/Shavano/inductor-info.html
Greetings from Germany
Jürgen
I insist guys ... no EMI or RF noises from my Kit from www.Autocostruire.com. Even if I keep it on the desk between computers and neon lamps ..... so what's the problem?
Keep in mind also that EMI waves decay exponentially, so it's really unlike that you'll induce disturbances on other equipment.
Yesterday, solicited by all these discussions, I tried wondering with an oscilloscope probe around the kit. Well, you can catch some high frequency "carrier" when the tip is near the air core inductors, but it rapidly decays to zero if you move out of the core. I was unable to trigger the frequency properly (I have a 20 MHz scope), so probably it's a "spread spectrum" carrier that's outside the audio band. This is in accordance with what you find in the Tripath docs.
I also downloaded an interesting application note where the nature of "clipping" is described ... see http://www.tripath.com/downloads/an6.pdf.
So, if any "carrier" residual is still present, it should make no harm at the sound quality. Take a look at the application note ... have you ever seen an amp that stands the clipping in such a correct way ?
..... so what's the problem?Keep in mind also that EMI waves decay exponentially, so it's really unlike that you'll induce disturbances on other equipment.
Yesterday, solicited by all these discussions, I tried wondering with an oscilloscope probe around the kit. Well, you can catch some high frequency "carrier" when the tip is near the air core inductors, but it rapidly decays to zero if you move out of the core. I was unable to trigger the frequency properly (I have a 20 MHz scope), so probably it's a "spread spectrum" carrier that's outside the audio band. This is in accordance with what you find in the Tripath docs.
I also downloaded an interesting application note where the nature of "clipping" is described ... see http://www.tripath.com/downloads/an6.pdf.
So, if any "carrier" residual is still present, it should make no harm at the sound quality. Take a look at the application note ... have you ever seen an amp that stands the clipping in such a correct way ?
My fears have definitely been allayed. I have just tried the Autocostruire air-cored inductors on my T-Amp and they sound great! It has really cleaned the treble up. Up to now, there were only 2 areas in which my existing amp beat the T-Amp (modded with 4.7uF caps, no I/P inductors, 12V car battery powered, decent case/connectors, no volume pot) and that was the treble which was a bit rough/grainy/overpowering and the bass which is lacking in “clout”. The treble is now silky smooth, so clearly the radiation “problem” does not seem to be a problem. No screens or shields necessary.
Hopefully putting some big caps across the battery will lower the ESR and improve the bass. I certainly hope so as the little amp is now so good, that even with the bass problem, it’s hard to go back to my trusty old amp. (Onix OA21 which is a very highly regarded transistor amp reckoned to sound as good as £1000 Naim amps)
Hopefully putting some big caps across the battery will lower the ESR and improve the bass. I certainly hope so as the little amp is now so good, that even with the bass problem, it’s hard to go back to my trusty old amp. (Onix OA21 which is a very highly regarded transistor amp reckoned to sound as good as £1000 Naim amps)
I own 3 sonic impacts and a Teac AL700 power amp which I use with a passive pre-amp. Out of curiosity more than anything as I've been delighted with the sonic impacts I ordered a pre-built t-amp on Sunday which was delivered on Thursday. Impatient I connected just the the circuit board up and wow! it has the attributes of the sonic impact but with astonishing dynamics and controlled bass extension and drive. My friend who owns a multi thousand £ Naim system (as I did previously) sat for 2 hours yesterday utterly entranced by this circuit board! as it drove my B&W CDM 9NTs with spine-tingling realism. Within weeks I've found a major leap in performance over the sonic impact which itself had set new standards in my system.
JWFokker said:
I have both a kit from Autocostruire and an original SI T-amp that i tried to improve .... the original SI product was clearly created to be low price and produced in big quantities, so no "custom" components on it like "air core" inductors .....
On the original t-amp you can find inductors that you can buy "off the shelf" for a reasonable price. Take a look at the pdf files from Tripath, they are chip makers, so they produce "reference designs" strictly based on currently available components .....
So I don't know if they really considered the option of "non standard" inductors: they are simply a problem if you want to make "mass production".
Up to this moment I believe to my ears: the "air core" inductors are simply superior, that's all. Maybe in the future someone will do even better, who knows ... but for now I see a clear winner
After all, we are all looking for the best sound we can get, and so customisation is the way to go .... or are we trying to sell million units?
www.autocostruire.it sell the t-amp either in kit form for self build or pre-assembled less the case and power supply for just a few euros more. I chose the latter hence why we could test the amp immediately thought it did look rather strange - a circuit board hooked up to my floorstanders. We both agreed that the t-amp plus B&W CDM9NTs was far better than my friends Naim 250 plus Monitor Audio 20s (?). We were completely entranced by Riders on The Storm, Awaken (Yes) and many many others - clarity, dyamics, driving rythmn, bass power . The only area it may not significantly surpass the Sonic Impact is in the pinpoint placement of vocals, drums etc between speakers that the SI demonstrates to startling effect - but it has more a 3D quality.
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